package com.TT.ticket.pc;


import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 线程之间的通信问题：生产者和消费者问题!  等待唤醒，通知唤醒
 * 线程交替执行  A  B 操作同一个变量   num=0
 * A  num+1
 * B  num-1
 */
public class B {
    public static void main(String[] args) {
        Data2 data = new Data2();


        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.increatment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "A").start();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.decreatment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "B").start();
    }
}


/**
 * 判断等待，业务，通知
 */

/**
 * 如果是多个线程，使用if判断会产生虚假唤醒问题，所以改为while即可解决
 */
class Data2 {  //数字 资源类

    private int number = 0;

    Lock lock = new ReentrantLock();

    Condition condition = lock.newCondition();

//        condition.await(); //等待
//        condition.signalAll();  //唤醒全部


    //+1
    public void increatment() throws InterruptedException {
        lock.lock();
        try {
            while (number != 0) {
                //等待
                condition.await();
            }
            number++;
            System.out.println(Thread.currentThread().getName() + "=>" + number);
            //通知其他线程，我+1完毕了
            condition.signalAll();
        } catch (Exception e) {
            e.printStackTrace();

        } finally {
            lock.unlock();
        }
    }

    //-1
    public void decreatment() throws InterruptedException {
        lock.lock();
        try {

            while (number == 0) {
                //等待
                condition.await();
            }
            number--;
            System.out.println(Thread.currentThread().getName() + "=>" + number);
            //通知其他线程，我-1完毕了
            condition.signalAll();
        } catch (Exception e) {
            e.printStackTrace();

        } finally {
            lock.unlock();
        }
    }

}
